getAllLongestStrings-1.js

// Given an array of strings, return another array containing all of its longest strings.
function getAllLongestStrings(inputArray) {}

getAllLongestStrings-1.spec.js

describe('getAllLongestStrings', () => {
  it('should be empty if a given inputArray is empty', () => {
    // Arrange
    const inputArray = [];

    // Act
    const result = getAllLongestStrings(inputArray);

    // Assert
    expect(result).to.be.empty;
  });
});

getAllLongestStrings-2.js

function getAllLongestStrings(inputArray) {
  if (!inputArray.length) {
      return [];
  }
}    

getAllLongestStrings-2.spec.js

describe('getAllLongestStrings', () => {
  it('should be empty if a given inputArray is empty', () => {
    const inputArray = [];
    const result = getAllLongestStrings(inputArray);
    expect(result).to.be.empty;
  });
  
  it('should be empty if a given inputArray is not an array', () => {
    const inputArray = null;
    const result = getAllLongestStrings(inputArray);
    expect(result).to.be.empty;
  });
});

getAllLongestStrings-3.js

function getAllLongestStrings(inputArray) {
  if (!Array.isArray(inputArray) || !inputArray.length) {
      return [];
  }
}

getAllLongestStrings-3.spec.js

describe('getAllLongestStrings', () => {
  it('should be defined as function', () => {
      expect(getAllLongestStrings).to.be.a('function');
  });

  it('should be empty if a given inputArray is empty', () => {
      const inputArray = [];
      const result = getAllLongestStrings(inputArray);
      expect(result).to.be.empty;
  });

  it('should be empty if a given inputArray is not an array (null)', () => {
      const inputArray = null;
      const result = getAllLongestStrings(inputArray);
      expect(result).to.be.empty;
  });

  it('should be empty if a given inputArray is not an array (undefined)', () => {
      const inputArray = undefined;
      const result = getAllLongestStrings(inputArray);
      expect(result).to.be.empty;
  });

  it('should return the longest strings in a given inputArray', () => {
      const inputArray = ['aba', 'aa', 'ad', 'vcd', 'aba'];
      const expected = ['aba', 'vcd', 'aba'];
      const result = getAllLongestStrings(inputArray);
      expect(result).to.deep.equal(expected);
  });

  it('should return the longest strings in a given inputArray even if it has a single element', () => {
      const inputArray = ['aba'];
      const expected = ['aba'];
      const result = getAllLongestStrings(inputArray);
      expect(result).to.deep.equal(expected);
  });
});

getAllLongestStrings-4.js

function getAllLongestStrings(inputArray) {
  if (!Array.isArray(inputArray) || !inputArray.length) {
      return [];
  }

  const [first, ...array] = inputArray;

  return array.reduce((result, current) => {
      if (result[0].length === current.length) {
          result.push(current);
      }

      if (result[0].length < current.length) {
          result = [current];
      }

      return result;
  }, [first]);
}